The present invention relates to pumps for dispensing liquids and, more particularly, to a manually actuated pump having no check valves and a minimum number of parts, yet which is capable of developing sufficiently high pressures to facilitate atomization of liquids which are considered difficult to spray. Importantly, the high pressure is developed externally of the container of liquid to be sprayed.
Present concern over the harmful effects of aerosol sprays on health and environment have led to a need for a simple replacement pump. Such a pump must be capable of being sold as a part of a container of dispensable liquid and must be sufficiently inexpensive to be feasibly discarded when the container is empty. Most otherwise suitable pumps require one or more check valves which tend to wear out and significantly reduce operating life. Others require numerous parts and are costly to manufacture, often rendering the pump more costly than the material to be sprayed. Still other pumps develop high pressures within the container of liquid, thereby requiring re-enforced and expensive containers.
It is therefore an object of the present invention to provide an inexpensive hand-operated pump serving as a seal for a liquid container and which develops high pressures in the pump but not in the container.
It is another object of the present invention to provide an inexpensive pump requiring no check valves.
It is a further object of the present invention to provide an inexpensive pump having a minimum number of parts with only one part being movable.
It is still another object of the present invention to provide an efficient spray pump which is capable of mass production by injection molding techniques.